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/*******************************************************************************
* Copyright (c) 2000, 2004 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.dnd;
import org.eclipse.swt.internal.Converter;
import org.eclipse.swt.internal.gtk.OS;
/**
* <code>Transfer</code> provides a mechanism for converting between a java
* representation of data and a platform specific representation of data and
* vice versa. It is used in data transfer operations such as drag and drop and
* clipboard copy/paste.
*
* <p>You should only need to become familiar with this class if you are
* implementing a Transfer subclass and you are unable to subclass the
* ByteArrayTransfer class.</p>
*
* @see ByteArrayTransfer
*/
public abstract class Transfer {
/**
* Returns a list of the platform specific data types that can be converted using
* this transfer agent.
*
* <p>Only the data type fields of the <code>TransferData</code> objects are filled
* in.</p>
*
* @return a list of the data types that can be converted using this transfer agent
*/
abstract public TransferData[] getSupportedTypes();
/**
* Returns true if the <code>TransferData</code> data type can be converted
* using this transfer agent.
*
* @param transferData a platform specific description of a data type; only the data
* type fields of the <code>TransferData</code> object need to be filled in
*
* @return true if the transferData data type can be converted using this transfer
* agent
*/
abstract public boolean isSupportedType(TransferData transferData);
/**
* Returns the platform specfic names of the data types that can be converted
* using this transfer agent.
*
* @return the platform specfic names of the data types that can be converted
* using this transfer agent.
*/
abstract protected String[] getTypeNames();
/**
* Returns the platform specfic ids of the data types that can be converted using
* this transfer agent.
*
* @return the platform specfic ids of the data types that can be converted using
* this transfer agent
*/
abstract protected int[] getTypeIds();
/**
* Converts a java representation of data to a platform specific representation of
* the data.
*
* <p>On a successful conversion, the transferData.result field will be set as follows:
* <ul>
* <li>Windows: COM.S_OK
* <li>Motif: 1
* <li>GTK: 1
* <li>Photon: 1
* </ul></p>
*
* <p>If this transfer agent is unable to perform the conversion, the transferData.result
* field will be set to a failure value as follows:
* <ul>
* <li>Windows: COM.DV_E_TYMED or COM.E_FAIL
* <li>Motif: 0
* <li>GTK: 0
* <li>Photon: 0
* </ul></p>
*
* @param object a java representation of the data to be converted; the type of
* Object that is passed in is dependant on the <code>Transfer</code> subclass.
*
* @param transferData an empty TransferData object; this object will be
* filled in on return with the platform specific representation of the data
*/
abstract protected void javaToNative (Object object, TransferData transferData);
/**
* Converts a platform specific representation of data to a java representation.
*
* @param transferData the platform specific representation of the data to be
* converted
*
* @return a java representation of the converted data if the conversion was
* successful; otherwise null. The type of Object that is returned is dependant
* on the <code>Transfer</code> subclass
*/
abstract protected Object nativeToJava(TransferData transferData);
/**
* Registers a name for a data type and returns the associated unique identifier.
*
* <p>You may register the same type more than once, the same unique identifier
* will be returned if the type has been previously registered.</p>
*
* <p>Note: On windows, do <b>not</b> call this method with pre-defined
* Clipboard Format types such as CF_TEXT or CF_BITMAP because the
* pre-defined identifier will not be returned</p>
*
* @param formatName the name of a data type
*
* @return the unique identifier associated with this data type
*/
public static int registerType(String formatName){
if (formatName == null) return OS.GDK_NONE;
byte[] buffer = Converter.wcsToMbcs(null, formatName, true);
return (int)/*64*/OS.gdk_atom_intern(buffer, false);
}
}
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